1. Field of Invention
The present invention relates to the switch technology in the wireless communication, in particular to a method for switching of multi-mode mobile user equipment (UE) and IMS (IP Multimedia Subsystem) terminal between 3rd Generation Mobile Communication (3G) system and World Interoperability for Microwave Access (WiMAX) system.
2. Description of Prior Art
Recently, mobile communication has been the focus of the communication technology research at all times. With the 3G system entering the commercial operation stage gradually, the service requirements for more abundant content and higher service quality have been raised based on the capability of UE for providing conventional mobile voice and short message service and narrowband data service. As a result, it is required that the UE has the capability of interacting with various networks with different modes, and that UE is enabled to support mobile multimedia services.
At present, the main differences between UE in 3G system and that in most of the prior 2G systems are embodied in: the increase of speed in the voice and data transmission, the capability of the UE in 3G system for processing the media of various forms, such as image, music, video stream, etc., providing various information services including web page browsing, telephone meeting, electronic commercial, etc. However, in order to provide such multimedia services, mobile communication network must have the capability of supporting different data transmission rates. Normally, the network in the indoor, outdoor and driving environment is required to support at least the rate of 2 Mbps (megabyte per second), 384 kbps (kilobyte per second) and 144 kbps, respectively. However, in comparison with accessing the mobile communication network by the UE and using the broadband multimedia services provided by it, accessing the fixed network by the UE and using the broadband multimedia services has obvious advantages in the aspects of bandwidth, stability and price undoubtedly.
The mobile multimedia service with high real-time requirement in the UE services is the presently accepted so-called next killer application in the industry. As such, 3GPP first raised IP Multi-media Subsystem (IMS) mobile terminal technology in the R5 (Release 5) version in June 2002, and kept on improving its application standards in the subsequent R6 and R7 versions. 3GPP constituted IMS as the core technical standard of the 3G system at first, and now IMS has been accepted by ITU-T and ETSI and has been incorporated into the core standard framework of Next Generation Network (NGN), which is believed to be the important technical basis for realizing the future fixed/mobile network combination (FMC), in which FMC is the technology providing communication services by combining fixed and wireless technology.
As the multi-mode UE in 3G system is able to implement mobile services through various wireless access network systems in various application environments, the terminal providers and network devices manufacturers need to support the switch of the UE that can implement IMS service between various wireless network systems to obtain the services with quicker data transmission rate, better quality of service (QoS) and cheaper price and to make the users not to feel the interruption and stall in the multimedia communication services, that is to say, to realize seamless switch. The common wireless access networks include: Wi-Fi, also represented as WLAN, utilizing IEEE 802.11 series protocols, WiMAX system utilizing IEEE 802.16 series protocols, ultra-wideband (UWB) technology, Universal Mobile Communication System (GSM), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access 2000 (CDMA2000) system, etc.
At present, the FMC technology receives much concern, and the WiMAX technology having the properties of the wireless MAN is believed to be the powerful weapon of the fixed network for the competition with the 3G technology by providing and extending the wireless broadband access service. WiMAX is also called Broadband Wireless Access (BWA), which is the IEEE 802.16 standard constituted by IEEE, belonging to the WMAN technology which is a new air interface raised for the microwave and millimeter-wave band for connecting the WLAN wireless access point to Internet, connecting company and home LAN to wired backbone line, and being the wireless extending technology for the cable line and xDSL to realizing wireless broadband access.
As the antenna of the WiMAX system with the properties of the wireless MAN has the coverage radius up to 30 miles with its data rate up to 70 Mbps, which have the obvious advantages in the aspects of the network coverage cost and bandwidth compared with the 3G system, and the WiMAX system can be combined with the existing 3G system in the future 4G mobile communication stage, how the UE supporting IMS services switches seamlessly between the 3G system and the WiMAX system is subject to the attention of the industry presently.
In the prior art, the switch mechanisms between different networks primarily start from the core network (CN), with the relatively complex procedure, long communication time, and switch quality difficult to be guaranteed, thus causing the problems of long switch time, more occupied resource, etc. For the IMS services which are very sensitive to the real-time property and the resource occupation, it is also very necessary to find a simple, convenient and practical switch scheme.
FIG. 1 is a schematic diagram of a loose coupling interactive manner between the WiMAX system of the prior art and the 3GPP core network. As shown in FIG. 1, the thought of the proposal is: on the basis that the IMS service is the technology over all-IP, designing a control protocol between the WiMAX system service providing device and the 3GPP core network for negotiating to call the IMS data in the respective servers in Internet, changing the IMS data transmission path by the respective control signaling to implement the switch between the 3G system and the WiMAX system. It is called the loose coupling manner, because the proposal adopts the negotiation in the step of IMS data source control, while the access layer and even the mobile terminal only participate the data transmission passively. With this coupling manner, in order to realize the IMS data control negotiation between the 3G system and the WiMAX system, it is needed to make a more complex design for the control protocol between the WiMAX system service providing device and the 3GPP core network (represented as dashed line in FIG. 1), with its access layer and mobile terminal part not participating switch control but conducting dual-link switch in term of control signaling passively. As such, in operation, the control signal interaction between the system network elements is relatively complex, the switch time is relatively long, and the real-time performance is relatively poor.
The technology related to the switch between the 3G system and the WLAN system and the switch technology of the user terminal within the WiMAX system are conventional technologies. However, these conventional technologies don't relate to the technology of participating the switch control by the UE, and the technical schemes all let the network side to be the leading role in the switch control and let the UE only receive the control signaling from the network side and conduct dual-link switch passively. Thus, how to enable the multi-mode UE to participate the active switch control flow between different networks or even to lead the switch control between different networks for realizing the further improvement of the switch efficiency is a problem to be solved at present.